Aqueous Production Research Articles

Ocular surface response of two preservative-free cylcosporine A emulsion eye drops in a mouse model of dry eye

ABSTRACT Purpose/Aim Dry eye (DE) disease is a multifactorial disease in which uncontrolled inflammation can lead to corneal epithelium lesions and symptoms of discomfort. The aim of the present study was to evaluate the efficacy of two cyclosporine emulsions in a mouse model of DE with corneal epithelium lesions. Materials and Methods Six- to 9-week-old female C57BL/6 N mice were housed in a controlled-environment room to induce DE. Following DE development, mice were instilled with: QD 0.1%CsA cationic emulsion (CaEm), BID 0.05%CsA anionic emulsion (AEm), or left untreated. Aqueous tear production and corneal epithelium lesions were assessed throughout the experiment. At the end of the treatment period, left eyes were sampled, fixed, and stained for histology, while the cornea, conjunctiva, and lacrimal gland of right eyes were sampled for transcriptomic analysis. Results Corneal lesion scores were reduced by 10.4%, 18.4%, and 10.9% at day 6, 10, and 14, respectively, with CaEm (QD), and by 2.6%, 3.0%, and 5.5% at day 6, 10, and 14, respectively, with AEm (BID). Histology demonstrated that 7 out of 10 DE mice presented moderate to severe ocular lesions, while only 2 and 5 out of 10 mice presented slight to moderate ocular lesions when treated with the CaEm (QD) and AEm (BID), respectively. The transcriptomic profile analysis suggests that a different set of inflammatory genes are modulated in the cornea, conjunctiva, and lacrimal gland upon DE development. In addition, the two emulsions distinctively modulate the gene expression profile. Conclusions This study demonstrates that both emulsions were effective at reducing corneal lesions, with the CaEm (QD) being slightly better than the AEm (BID). Interestingly, this study suggests that ocular tissues may not respond similarly to a dry environment and that a different set of genes is modulated by the two formulations in the ocular tissues.

Aqueous production of secondary organic aerosol from fossil-fuel emissions in winter Beijing haze

Secondary organic aerosol (SOA) produced by atmospheric oxidation of primary emitted precursors is a major contributor to fine particulate matter (PM2.5) air pollution worldwide. Observations during winter haze pollution episodes in urban China show that most of this SOA originates from fossil-fuel combustion but the chemical mechanisms involved are unclear. Here we report field observations in a Beijing winter haze event that reveal fast aqueous-phase conversion of fossil-fuel primary organic aerosol (POA) to SOA at high relative humidity. Analyses of aerosol mass spectra and elemental ratios indicate that ring-breaking oxidation of POA aromatic species, leading to functionalization as carbonyls and carboxylic acids, may serve as the dominant mechanism for this SOA formation. A POA origin for SOA could explain why SOA has been decreasing over the 2013-2018 period in response to POA emission controls even as emissions of volatile organic compounds (VOCs) have remained flat.

Comparison between conventional solvothermal and aqueous solution-based production of UiO-66-NH2: Life cycle assessment, techno-economic assessment, and implications for CO2 capture and storage

Metal-organic frameworks (MOFs) are a new class of materials that has shown great potential in catalysis, sensing, separations, and carbon capture and storage. Conventionally, MOFs are synthesized at lab-scale using organic solvent-based systems, leading to high environmental burdens and high operating costs, which ultimately hinders the large-scale production and application of MOFs. Aqueous synthesis of MOFs overcomes such difficulty by eliminating the organic solvent, which makes it an environmental-friendlier and economically-favorable alternative to the current production method. However, further quantitative analysis is required to compare the environmental and economic performances of the two methods. Here, we used life cycle assessment (LCA) coupled with techno-economic analysis (TEA) to evaluate the environmental and economic performances of different UiO-66-NH2 production methods. When the solvothermal method was replaced by the aqueous solution-based method, the LCA and TEA results suggest the environmental burdens and cost of UiO-66-NH2 production were reduced by up to 91% and 84%, respectively. By using aqueous solution-based method, the cradle to gate carbon footprint, and production cost of UiO-66-NH2 were estimated to be 43 kg CO2 eq/kg, and $15.8/kg, respectively. We further applied our LCA results to reassess the role of UiO-66-NH2 in carbon capture and storage (CCS) and compare its environmental performance with current benchmark (amine-based solvent). Our results show that electricity produced from UiO-66-NH2 CCS system could potentially have better environmental performance (lower Global Warming Potential (GWP)) than that of the amine-based CCS system if the sorbent loss is less than 0.0017 tonne/tonne CO2 captured. This work is the first comprehensive LCA-TEA study that quantifies the substantial environmental and economic benefits of using the aqueous solution-based systems to produce UiO-66-NH2, and the analysis in this work is intended to be a starting point for further systematic studies on the full life-cycle impacts of MOFs.

Netarsudil Improves Trabecular Outflow Facility in Patients with Primary Open Angle Glaucoma or Ocular Hypertension: A Phase 2 Study

Intraocular pressure (IOP) reduction is key to controlling primary open angle glaucoma (POAG). Pharmacotherapies for POAG or ocular hypertension (OHT) commonly lower IOP by increasing uveoscleral outflow or decreasing aqueous humor production. Netarsudil (Rhopressa), a Rho kinase inhibitor, reduces IOP by improving trabecular outflow facility, which is reduced in POAG. We investigated the effects of netarsudil on aqueous humor dynamics in patients with POAG or OHT. Double-masked, randomized, vehicle-controlled, Phase 2 trial. Netarsudil 0.02% was instilled in 1 eye and vehicle into the contralateral eye of 20 patients once daily in the morning for 7 days. The primary endpoint was change in mean diurnal outflow facility on day 8 versus that on day 1 (baseline). Outflow facility was measured by using Schiøtz tonography, IOP by pneumotonometry, and episcleral venous pressure (EVP) by automated venomanometry. Eighteen patients (90%) completed the study. Mean diurnal outflow facility increased 0.039 versus 0.007 µL/min/mm Hg from baseline in the netarsudil- and the vehicle-treated groups, respectively (P < .001 vs. baseline for netarsudil), a treatment difference of 0.03 µL/min/mm Hg (P ≤ .001). Mean diurnal IOP change from baseline at day 8 was -4.52 mm Hg for netarsudil versus -0.98 mm Hg for vehicle, a treatment difference of -3.54 mm Hg (P < .0001). Mean diurnal EVP change from baseline was -0.79 mm Hg in the netarsudil-treated group versus 0.10 mm Hg for vehicle, a treatment difference of -0.89 mm Hg (P < .001). All patients reporting an adverse event reported conjunctival hyperemia of mild or moderate severity. Netarsudil acts on the conventional outflow pathway, both proximal and distal, to significantly reduce IOP in POAG and OHT by improving trabecular outflow facility and decreasing EVP.

Endocrine Dysfunction in Open Angle Glaucoma.

The eye, like all organs, is exposed to the effects of the body's endocrine system. In addition, however, local branches of the endocrine system control important organ-specific functions, such as the production and drainage of aqueous humour. Similarly, the eye as a sensory organ acts back on endocrine controlled functions of the body, for example the day-night rhythm. This article aims to illustrate the physiological and pathological interactions of the eye and the endocrine functions of the body in the context of glaucoma. 1. The renin-angiotensin-aldosterone system, which as a local system is involved in the control of aqueous humour production and outflow. 2.The hormone endothelin, which as a strong vasoconstrictor plays a role in the dysregulated perfusion of the optic nerve and retina, and 3.the disruption of the day-night rhythm in advanced glaucoma, which is thought to be caused by damage to light-sensitive ganglion cells.

Aqueous Elemental Mercury Production versus Mercury Inventories in the Lake Michigan Airshed: Deciphering the Spatial and Diel Controls of Mercury Gradients in Air and Water

Atmospheric delivery of mercury (Hg) is important to the Upper Great Lakes, and understanding gaseous Hg exchange between surface water and air is critical to predicting the effects of declining me...

A review of glaucoma surgical therapy.

Glaucoma is a disorder of all species due to a rise of intraocular pressure (IOP) beyond which is compatible with ganglion cell and axon function, often resulting in optic nerve degeneration and irreversible blindness. Glaucoma treatment with surgical intervention aimed at either reducing aqueous production, or increasing or altering aqueous outflow has evolved over preceding decades, but there remains no cure. The present article is intended to provide a concise review of glaucoma surgical therapies in veterinary ophthalmology.

The Impact of Surgical Excision of the Orbital Lacrimal Gland on the Aqueous Tear Production and Ocular Surface Health in Donkeys (Equus asinus)

The exact contribution of the orbital lacrimal gland (OLG) is unknown and is still a subject of debate and inconsistency in literature. Currently, there are no detailed studies addressing the influence of the OLG removal on tear production in equines. This study aimed to address the influence of surgical excision of the OLG on aqueous tear production and ocular surface health in donkeys. The study was conducted on six clinically healthy donkeys with no ophthalmic abnormalities. In each donkey, the OLG of the left eye was surgically excised, whereas the right eye was served as a control. External ophthalmic examination, Schirmer tear test (STT) I and II, tear pH, fluorescein staining test were conducted on both eyes, preoperatively and at one-week intervals for 60 days, postoperatively. There were significant decreases in STT I and II values (P = .0001 and .0001, respectively), whereas tear pH values showed a significant increase (P = .0001) in the operated eyes compared with the control ones. There were no overt clinical signs characteristics of keratoconjunctivitis sicca (KCS) in the operated eyes. However, there was evidence of microinjury of the keratoconjunctival epithelium evidenced by positive fluorescein uptake, postoperatively. Surgical excision of the OLG significantly diminished the aqueous tear production and threatened the corneal epithelium as a result of corneal dehydration. On the contrary to the recommendations of other studies, eyes subjected to this procedure should receive treatment of dry eye to prevent development of KCS, postoperatively.

Obese Mice with Dyslipidemia Exhibit Meibomian Gland Hypertrophy and Alterations in Meibum Composition and Aqueous Tear Production.

Background: Dyslipidemia may be linked to meibomian gland dysfunction (MGD) and altered meibum lipid composition. The purpose was to determine if plasma and meibum cholesteryl esters (CE), triglycerides (TG), ceramides (Cer) and sphingomyelins (SM) change in a mouse model of diet-induced obesity where mice develop dyslipidemia. Methods: Male C57/BL6 mice (8/group, age = 6 wks) were fed a normal (ND; 15% kcal fat) or an obesogenic high-fat diet (HFD; 42% kcal fat) for 10 wks. Tear production was measured and meibography was performed. Body and epididymal adipose tissue (eAT) weights were determined. Nano-ESI-MS/MS and LC-ESI-MS/MS were used to detect CE, TG, Cer and SM species. Data were analyzed by principal component analysis, Pearson’s correlation and unpaired t-tests adjusted for multiple comparisons; significance set at p ≤ 0.05. Results: Compared to ND mice, HFD mice gained more weight and showed heavier eAT and dyslipidemia with higher levels of plasma CE, TG, Cer and SM. HFD mice had hypertrophic meibomian glands, increased levels of lipid species acylated by saturated fatty acids in plasma and meibum and excessive tear production. Conclusions: The majority of meibum lipid species with saturated fatty acids increased with HFD feeding with evidence of meibomian gland hypertrophy and excessive tearing. The dyslipidemia is associated with altered meibum composition, a key feature of MGD.

Vitamin D and Glaucoma: A Critical Review of the Literature

Primary open-angle glaucoma is a progressive optic neuropathy which can lead to irreversible blindness if untreated. A number of studies have been published suggesting a correlation between the level of serum vitamin D3 and glaucoma or intraocular pressure (IOP). The latter is known to be a major risk factor for glaucoma and is the main target of glaucoma treatment. We give a critical review of the literature, exploring what is known about this matter. While some studies report an inverse association between serum vitamin D3 and IOP, others do not confirm this finding. Similar divergent conclusions came from studies regarding the association between serum vitamin D3 and the presence or severity of glaucoma. The effect of vitamin D3 on IOP decrease has been attributed to both aqueous humor production and trabecular meshwork outflow pathway increase. Vitamin D3 has been shown to play a major role in reducing inflammation, modulating the immune response, and decreasing angiogenesis in the eye and in other organs. It has been suggested that, through its neuroprotective effect, vitamin D3 could be a protective factor for glaucoma and that vitamin D3 deficiency could explain glaucoma occurrence or severity in some patients. Other neurodegenerative diseases such as Alzheimer’s disease and multiple sclerosis have been similarly related to vitamin D3 deficiency. 1α,25(OH)2 vitamin D3 (calcitriol) supplementation has been shown to be beneficial for lowering IOP in monkeys. Although the studies highlighted in this review show interesting results, their limitations underscore the need for both population-based studies and larger randomized controlled trial with vitamin D3 supplementation. The specific role of vitamin D3 in the pathology of glaucoma remains to be elucidated, together with the possible therapeutic benefit of vitamin D3 supplementation.

Medical anti-glaucoma therapy: Beyond the drop.

Barriers to effective medical therapy are numerous and include difficulties with effective and sustained control of intraocular pressure (IOP) and adherence to prescribed anti-glaucoma drop regimens. In an effort to circumvent these challenges, a number of new anti-glaucoma therapies with sustained effects have emerged. Methods for sustained delivery of prostaglandin analogs are being intensely investigated and many are in human clinical trials. Intracameral devices include the following: Allergan's Durysta™ Bimatoprost SR, Envisia Therapeutics' ENV515 travoprost implant, Glaukos' iDose™ , Ocular Therapeutix's OTX-TIC travoprost implant, and Santen's polycaprolactone implant with PGE2-derivative DE-117. Other prostaglandin-based technologies include Allergan's bimatoprost ring (placed in the conjunctival fornix), Ocular Therapeutics' OTX-TP intracanalicular travoprost implant, subconjunctival latanoprost in a liposomal formulation, and the PGE2 derivative PGN 9856-isopropyl ester that is applied to the periorbital skin. Exciting breakthroughs in gene therapy include using viral vectors to correct defective genes such as MYOC or to modulate gonioimplant fibrosis, CRISPR technology to edit MYOC or to alter aquaporin to reduce aqueous humor production, and siRNA technology to silence specific genes. Stem cell technology can repopulate depleted tissues or, in the case of Neurotech's Renexus® NT-501 intravitreal implant, serve as a living drug delivery device that continuously secretes neurotrophic factors. Other unique approaches involve nanotechnology, nasal sprays that deliver drug directly to the optic nerve and noninvasive alternating current stimulation of surviving cells in the optic nerve. Over time these modalities are likely to challenge the preeminent role that drops currently play in the medical treatment of glaucoma in animals.

Aqueous humour outflow imaging: seeing is believing.

Elevated intraocular pressure (IOP) is the primary risk factor for blindness in glaucoma. IOP is determined by many factors including aqueous humour production and aqueous humour outflow (AHO), where AHO disturbance represents the primary cause of increased IOP. With the recent development of new IOP lowering drugs and Minimally Invasive Glaucoma Surgeries (MIGS), renewed interest has arisen in shedding light on not only how but where AHO is occurring for the trabecular/conventional, uveoscleral/unconventional, and subconjunctival outflow pathways. Historical studies critical to understanding outflow anatomy will be presented, leading to the development of modern imaging methods. New biological behaviours uncovered by modern imaging methods will be discussed with relevance to glaucoma therapies emphasized.

Adhesive tape-assisted etching of silk fibroin film with LiBr aqueous solution for microfluidic devices

The regenerated silk fibroin (RSF)-based microfluidic device has attracted tremendous interests in recent years due to its excellent biocompatibility, mild processing conditions, and all aqueous casting production. However, the need of a micro-fabricated mold in the manufacture process greatly hinder its practical applications. Herein, we introduce an adhesive tape-assisted etching method with LiBr solution as the etchant to prepare RSF microfluidic devices. An engraved adhesive tape is used as the mask to cover on the surface of a RSF film. Then, LiBr solution is dropped on the mask to etch RSF in concentration- and duration-dependent manners. During this process, the LiBr-treated RSF transits from insoluble β-sheet crystallites to soluble conformations. The as-prepared RSF microfluidic devices possess good chemical resistance and excellent tolerance to mechanical deformation. RSF microfluidic systems with different patterns were fabricated to demonstrate the universality of the approach. A concentration gradient generator and a blood vessel-like channel were manufactured for the preparation of solutions with gradient pHs and the growth of living cells, respectively. The proposed strategy has great potentials in the facile fabrication of low-cost RSF microfluidic devices for tissue engineering and biomedical analysis.

Prophylactic anti-glaucoma therapy in dogs with primary glaucoma: A practitioner survey of current medical protocols.

To examine the use of prophylactic anti-glaucoma medications in the normotensive fellow eye in dogs with unilateral overt primary glaucoma by veterinary ophthalmology clinicians. A survey of veterinary ophthalmology clinicians was distributed over two international list serves servicing veterinary ophthalmologists, trainees, and individuals whose practice consisted primarily of ophthalmic patients. The survey was developed following analysis of historical and currently available medical options for control of intraocular pressure and for neuroprotection. Responses from 199 veterinary ophthalmology clinicians were evaluated. While a large variety of topical anti-hypertensive drugs and protocols were used, the most commonly used medications were aqueous humor production suppressors such as dorzolamide 2.0% ophthalmic solution, timolol 0.5% ophthalmic solution, and a combination product containing both drugs. Latanoprost 0.005% ophthalmic solution was used infrequently for prophylaxis by comparison. The majority of respondents do not use concurrent anti-inflammatory medications (61.22%), although a sizeable minority used prednisolone acetate, dexamethasone, or ketorolac as prophylactic treatment. Systemically administered ocular anti-hypertensive agents were rarely used. Only 40% of respondents used neuroprotectant agents; the most commonly prescribed were the calcium channel blocker amlodipine and the nutraceutical Ocu-Glo™. Recommended intervals between re-examination by the clinician ranged from one month to one year, with most re-evaluations occurring every 3 to 6months. The majority of respondents recommended more frequent assessments of IOP at intervals between once monthly and once every 3months. Data analysis of medical therapy for the normotensive fellow eye of dogs previously diagnosed with primary glaucoma suggests that there is a great need for well-designed, prospective, controlled, multi-center studies to determine which protocols have the greatest efficacy in delaying an overt attack in the previously normotensive eye in dogs with a genetic predisposition to glaucoma. Prospective studies utilizing a carbonic anhydrase inhibitor such as dorzolamide and a prostaglandin analogue such as latanoprost would be reasonable as these two drugs are widely used in the treatment of overt glaucoma and would allow for an exploration of the impact of different mechanisms of action of lowering IOP on the pathophysiology of primary glaucoma.

A Gram-Scale Limonene Production Process with Engineered Escherichia coli.

Monoterpenes, such as the cyclic terpene limonene, are valuable and important natural products widely used in food, cosmetics, household chemicals, and pharmaceutical applications. The biotechnological production of limonene with microorganisms may complement traditional plant extraction methods. For this purpose, the bioprocess needs to be stable and ought to show high titers and space-time yields. In this study, a limonene production process was developed with metabolically engineered Escherichia coli at the bioreactor scale. Therefore, fed-batch fermentations in minimal medium and in the presence of a non-toxic organic phase were carried out with E. coli BL21 (DE3) pJBEI-6410 harboring the optimized genes for the mevalonate pathway and the limonene synthase from Mentha spicata on a single plasmid. The feasibility of glycerol as the sole carbon source for cell growth and limonene synthesis was examined, and it was applied in an optimized fermentation setup. Titers on a gram-scale of up to 7.3 g·Lorg−1 (corresponding to 3.6 g·L−1 in the aqueous production phase) were achieved with industrially viable space-time yields of 0.15 g·L−1·h−1. These are the highest monoterpene concentrations obtained with a microorganism to date, and these findings provide the basis for the development of an economic and industrially relevant bioprocess.

Location of the Ciliary Ganglion within the Orbit

The ciliary ganglion (CG) is a parasympathetic ganglion located in the orbit that controls pupil contraction, accommodation, ocular blood flow, intraocular pressure, and aqueous humor production. Micro and macro‐surgical lesions to the CG can affect nearby structures and lead to Adie’s Tonic Pupil or Argyll Robertson Pupil. This study was performed to better understand the CG location within the orbit. Few studies have analyzed the distance from the CG to neighboring structures with evident variation in the mean distance between the posterior globe (PG) and the CG, which can prove clinically significant in orbital floor surgical procedures. Besides direct clinical impact, this research would be beneficial in medical education by enabling a more accurate depiction of the CG in anatomical illustrations. Lastly, this is a novel study in that it measures the distance in relation to a relatively immobile structure, rather than to a more dynamic and variable neural or vascular structure.MethodsNine cadaver heads were bisected for a total of 18 samples, and two additional bisected half heads were used. The calvaria, brain, cranial fossa dura matter, frontal bone, and lesser wing of sphenoid bone were removed. Once orbital contents were visualized, dissection began by identifying the anterior and posterior ethmoidal nerves that run superior to the upper border of the medial rectus muscle. Blunt dissection was used to trace them back to the nasociliary nerve, an ophthalmic nerve division. The nasociliary nerve sends a sensory root to the CG. The oculomotor nerve (CN III) passes through the common tendinous ring, which was dissected open to allow better visualization of CN III inferior and superior divisions. The inferior division of CN III, which carries parasympathetic contribution to the CG, was dissected. The CG was confirmed by tracing the sensory nasociliary branch and the parasympathetic root from the inferior division of CN III to CG. Once identified, the CG was pinned in the center, in its natural position. The distance from the PG at the optic nerve juncture and the pinned CG was measured three separate times, removing and placing the pin in the center for each measurement. The three measurements average was used. The second measurement was from the posterior clinoid process (PCP) to the pinned ganglion, measured three separate times, and the average was used for each ganglion.ResultsThe average distance range between PG and CG was 8.95 – 24.63 mm, with the average of the 20 mean measurements being 17.853 mm. The average distance range between CG and PCP was 28.23 – 39.58 mm, with the average of the 20 mean measurements being 35.135 mm.ConclusionThe distance from the PG to the CG center was 17.85 mm, and from CG center to PCP was 35.135 mm. This varies from other studies that have reported the distance between the PG and CG to be 12 mm, 2–3 mm, and 15–20 mm. The CG is 2.9 mm lateral to the optic nerve and could be damaged during lateral orbiotomy procedures. In terms of anatomical education, illustrations in Netter and Gray’s differ in the location of the CG. These results support Gray’s proposition that the CG is further posterior relative to the posterior globe rather than being closer to the globe as shown in Netter’s atlas. Ours is a novel study to clarify the position of the CG within the orbit.

Nitric oxide donating anti-glaucoma drugs: advances and prospects.

Glaucoma is a disease that causes irreversible blindness. Reducing intraocular pressure (IOP) is the main treatment at present. Nitric oxide (NO), an endogenous gas signaling molecule, can increase aqueous humor outflow facility, inhibit aqueous humor production thereby reducing IOP, as well as regulate eye blood flow and protect the optic nerve. Therefore, NO donating anti-glaucoma drugs have broad research prospects. In this review, we summarize NO-mediated therapy for glaucoma, and the state of the art of some NO donating molecules, including latanoprostene bunod in market and some other candidate compounds, for the intervention of glaucoma, as well as prospects and challenges ahead in this field.

Extracellular vesicle-mediated crosstalk between NPCE cells and TM cells result in modulation of Wnt signalling pathway and ECM remodelling.

Primary open‐angle glaucoma is a leading cause of irreversible blindness, often associated with increased intraocular pressure. Extracellular vesicles (EVs) carry a specific composition of proteins, lipids and nucleotides have been considered as essential mediators of cell‐cell communication. Their potential impact for crosstalk between tissues responsible for aqueous humour production and out‐flow is largely unknown. The study objective was to investigate the effects of EVs derived from non‐pigmented ciliary epithelium (NPCE) primary cells on the expression of Wnt proteins in a human primary trabecular meshwork (TM) cells and define the mechanism underlying exosome‐mediated regulation that signalling pathway. Consistent with the results in TM cell line, EVs released by both primary NPCE cells and NPCE cell line showed diminished pGSK3β phosphorylation and decreased cytosolic levels of β‐catenin in primary TM cells. At the molecular level, we showed that NPCE exosome treatment downregulated the expression of positive GSKβ regulator‐AKT protein but increased the levels of GSKβ negative regulator‐PP2A protein in TM cells. NPCE exosome protein analysis revealed 584 miRNAs and 182 proteins involved in the regulation of TM cellular processes, including WNT/β‐catenin signalling pathway, cell adhesion and extracellular matrix deposition. We found that negative modulator of Wnt signalling miR‐29b was abundant in NPCE exosomal samples and treatment of TM cells with NPCE EVs significantly decreased COL3A1 expression. Suggesting that miR‐29b can be responsible for decreased levels of WNT/β‐catenin pathway. Overall, this study highlights a potential role of EVs derived from NPCE cells in modulating ECM proteins and TM canonical Wnt signalling.

Urea-pretreated corn stover: Physicochemical characteristics, delignification kinetics, and methane production

Solids loading is a key factor in aqueous or gaseous ammonia production from urea. Methane production from urea-pretreated corn stover, as well as the physicochemical characteristics and delignification kinetics of the corn stover, were investigated with four solids loading values (10%–70%) and five ratios of urea to corn stover (1:100–7:10) at 35 °C for 6 weeks. A 1:20 ratio of urea to corn stover was optimal for achieving high lignin removal with ≤50% solids loading, and 7:10 was optimal with 70% solids loading. Under the two optimal conditions, 85.56% and 82.35% of cellulose and 85.76% and 85.49% of hemicellulose were retained. The maximum lignin removal rates of 69.67% and 68.27% and methane production of 294.70 and 292.56 L/kg volatile solids (VS) were achieved, respectively. The delignification kinetics of the urea-pretreated corn stover conformed to three first-order reactions. Most of the lignin was degraded within the first 3 weeks.

Aqueous deficiency is a contributor to evaporation-related dry eye disease

Dry eye disease aetiologies can be classified dichotomously into aqueous deficient and evaporative types although many cases involve combinations of both. Differential diagnosis can be confounded by some features of dry eye disease being common to both aetiologies. For example, short tear break-up times are prime diagnostic findings of tear instability due to lipid and/or mucin deficiencies, but thin tear layers in aqueous deficient eyes also shorten tear break-up times, even at normal range rates of evaporation in eyes without lipid and/or mucin deficiencies. Because tear instability and short tear film break-up times due to thin tear layers can be independent of lipid and/or mucin deficiency, aqueous deficiency can be another form of evaporation-related dry eye. Conversely, tear layers which are thickened by punctal occlusion can be less susceptible to tear break-up. An inflamed lacrimal gland producing reduced quantities of warmer tears can be a basis for thin tear layers and tear instability demonstrated by shorter tear break-up times. Commonly used clinical tests for aqueous deficiency can be unreliable and less sensitive. Consequently, failure to detect or confirm aqueous deficiency as a contributor to short tear break-up times could result in too much weight being given to a diagnosis of meibomian gland deficiency. Less successful treatment outcomes may be a consequence of failing to detect aqueous deficiency. Refining disease classification by considering aqueous deficiency as a contributor to, or even a form of evaporation-related dry eye, could be the basis for more comprehensive and appropriate treatment strategies. For example, some treatment methods for evaporation-related dry eye might be appropriate for aqueous and mucin-deficient as well as lipid-deficient dry eyes. Anti-inflammatory treatment for the lacrimal gland as well as the conjunctiva, may result in increased aqueous production, reduced tear temperature, tear instability and evaporation rates as well as lower osmolarity.